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By Ronald J. Roman

All mining and milling complexes can, within limits, operate at a variety of production rates. Factors of economic importance that are affected by production rates are costs per unit production, recovery and product grade. Once the relationship between the production rate and cost is established, dynamic programming techniques can be used to define the optimum production schedule (that is, the production schedule that maximizes the present worth of the operation) for the life of the deposit. In general, assuming that the capacity and efficiency of the physical plant remain unchanged throughout the life of the deposit, the optimum production rate is not constant for the life of the deposit, but declines gradually as the deposit is being exhausted.

Jan 1, 2014

By Z. Szczepanik, D. Milne, K. Kostakis

Abstract This paper presents the results of a series of creep tests performed on a total of nine samples of Lac du Bonnet granite from the Underground Research Laboratory near Pinawa, Canada. Each of the nine samples were subjected to stresses in excess of 80% of the average uniaxial compressive strength of the granite and were maintained at that level of constant loading for periods of time ranging between a few minutes and several months. Acoustic emission was recorded in order to monitor the development and accumulation of brittle microfracture damage in the samples throughout the long-term loading. According to previously published theoretical predictions and field results, as well as similar experimental results of creep tests in granite, samples should fail when loaded to 70% of their UCS for an extended period of time. Six of the samples did not fail when subjected to stresses in excess of 80% of their UCS over periods of several months and were subsequently subjected to uniaxial compression to failure. The average strength of the samples that had previously been subjected to long-term loading were comparable to the average published strength of this rock. Three of the nine samples had increased end confinement and these three samples failed under long term loading. Résumé Cet article présente les résultats d'une série d'essais de fluage de roche exécutés sur neuf échantillons de granite de Lac du Bonnet, du laboratoire souterrain de recherches près de Pinawa, Canada. Chacun des neuf échantillons a été alors soumis aux charges au-dessus de 80% de la résistance à la UCS moyenne du granit et a été maintenu à ce niveau du chargement constant pendant des périodes s'étendant entre quelques minutes et plusieurs mois. L'émission acoustique a été enregistrée pendant les essais afin d'obtenir des indications des dommages pendant le chargement à long terme. Selon des résultats théoriques précédemment édités et les résultats expérimentaux semblables des essais à long terme en granite, échantillons devrait échouer si chargé à 70% de leur UCS pendant une période prolongée. Six des échantillons n'ont pas cassé quant ils ont été soumis aux charges au-dessus de 80% de leur UCS et ont été plus tard soumis à la compression uniaxiale à la rupture. La force moyenne des échantillons qui avaient été précédemment soumis au chargement à long terme étaient comparable à la force éditée moyenne de cette roche. Trois des neuf échantillons avaient augmenté le confinement de fin et ces trois échantillons ont cassé sous le chargement à long terme. Zusammenfassung Dieser Artikel beschreibt die Resultate von Kriechversuchen, die an neun Proben aus dem Lac du Bonnet Granit des "Underground Research Laboratory" bei Pinawa in Kanada durchgeführt wurden. Jede der neun Proben wurde Drücken unterworfen, die mehr als 80% der einaxialen Druckfestigkeit des Granites entsprechen. Diese Drücke wurden für verschiedene Zeitspannen von wenigen Minuten bis zu einigen Monaten auf einem konstanten Niveau gehalten. Während der gesamten Langzeitbelastung wurden akustische Emissionen aufgezeichnet, um die Entwicklung und gesamthafte Beschädigung der Proben durch Sprödbruch aufzuzeichnen. Entsprechend bisher veröffentlichter theoretischer Vorhersagen, Feldversuchen und auch experimentellen Resultaten von Kriechversuchen an Granitproben wäre ein Versagen der Proben zu erwarten gewesen, wenn sie über längere Zeit einer Last von 70% ihrer einaxialen Druckfestigkeit unterworfen werden. Wider Erwarten trat bei sechs der Proben kein Versagen ein, als sie mit über 80% ihrer einaxialen Druckfestigkeit über mehrere Monate belastet wurden; daher wurden sie im Anschluss bei einaxialer Kompression zum Versagen gebracht. Die mittleren Festigkeiten der im Langzeittest verwendeten Proben sind vergleichbar mit den normalerweise für diesen Gesteinstyp angegebenen Festigkeiten. Drei der neun Proben versagten unter der Langzeitbelastung; diese drei Proben hatten eine erhöhte Endflächenreibung.

Jan 1, 2003

By A. N. Brown

The importance of the minerals industry in the economy of the country is discussed, and the tremendous changes that have taken place over the past two decades, including the widespread application of computers and the use of mechanization, are outlined. A discussion of the future of the minerals industry points out that, with the rise in the price of gold, the life of the gold-mining industry can be expected to extend beyond that previously predicted, and that the demand for uranium, which has been depressed, is uncertain. As a result of the oil crisis, the demand for coal has increased and large expansion programmes are planned. These involve coal exports and the use of coal for the generation of electric power, for the production of liquid fuels, and for the smelting of metals. Technical challenges face engineers in every avenue of the minerals industry: in deep gold mines, underground coal mines, strip coal mines, and open-pit mines. Studies indicate that only one-third of the demand for trained mining and metallurgical engineers is being met and that the position is worsening. However, there are indications that the industry is succeeding in attracting more engineering students, and the supply is expected to improve. These efforts should be co-ordinated, expanded, and intensified. There is a need to ensure that sufficient teaching staff of the right calibre and experience are attracted to universities and technikons. The first degree course is comprehensive and basic, and specialization through post-graduate study should be encouraged. The influence of national service on the education and training of engineers is discussed.

Jan 1, 1982

Stochastic methods are normally invoked / used to assist with the understanding of risks, when there is uncertainty around a particular outcome. Uncertainty implies that there is a risk that the desired outcome will not be realized. Stochastics and probability theory has long held out the promise to answering this need, but has often been maligned because of its misuse. This paper takes a critical look need for Monte Carlo simulation to project risk evaluation and highlights what is considered to be the fundamental issues that should be thoughtfully considered to avoid the abuse of this technique. The upside of avoiding the abuse of this technique will be the wider acceptance by practitioners that it is a credible technique to quantify this important aspect of valuation.

Jan 1, 2007

By H. S. Baloyi, J. J. Rust

Spiral concentrators are widely applied to beneficiate commodities such as Cr2O3, mineral sands, and ferrochrome. The application of spirals for heavy minerals has been limited to a feed top size of 1 mm. At particle sizes larger than this, friction retards heavy particles and the particles' primary velocity approaches zero, resulting in a solids build-up, therefore inhibiting further separation. Recently, a new Multotec SC25 spiral model was introduced to the industry, which aids in beneficiating particles of up to 3 mm, with successes having been demonstrated in ferrochrome slag and titanium-bearing minerals. This spiral also has potential in electronic waste applications. This paper examines the applicability of the SC25 spiral in coarse Cr2O3 recovery. This stems from the fact that junior chrome miners tend to discard particles larger than 1 mm as they neither have milling nor dense media circuits. Also, alluvial chrome miners discard +1 mm even though this size fraction contains recoverable and liberated Cr2O3. The SC25 spiral has shown better Cr2O3 separation efficiencies than the SC21 model and with higher SiO2 rejection at saleable grades, thus providing an additional revenue stream specifically for the coarser (+820 μm) size fractions. Keywords: Spiral concentrators, chromite recovery, specific gravity, SC25 spiral, coarse spiral

Jan 1, 2020

By T. Bhambhani, E. Arinaitwe

Solvay has developed several novel reagent innovations to improve separations in sulfide ore flotation and address major industry challenges. These innovations include: a) carbon management strategies to reduce the deleterious impact of organic carbon on flotation circuits; b) new collectors for heavily tarnished or oxidized Cu-Au ores; and c) a functionalized depressant for minimizing penalty elements in metal concentrates. Owing to their unique chemistries, these innovations exhibit a wide spectrum of rather unique properties that are quite in contrast to the traditionally used reagents. The chemistry, attributes, application, and advantages of these innovations are discussed in this paper based on laboratory, pilot, and plant results and observations for various ores

Jan 1, 2023

By G. Sánchez, S. Seiler, B. Klein, T. Cebeci, P. Bradshaw

The Decar Nickel District is a greenfield discovery by FPX Nickel Corp., of nickel mineralisation located in central British Columbia (BC), Canada. The Baptiste deposit is part of the Decar Nickel District and is a unique deposit containing a nickel-iron alloy mineral called awaruite, with over 2-billion tonnes of inferred resource grading 0.12% Davis Tube Recoverable (DTR) nickel. This deposit represents a significant nickel resource. Awaruite is a high density and ferromagnetic mineral, which could be recovered, along with magnetite that is also present in the samples, using magnetic separation. However, there is still a lack of understanding of the properties of the awaruite and its metallurgical response. This information is imperative for the set-up of the variables involved in its concentration. The aim of this paper is to show and discuss the effect of magnetic field strength for the recovery of nickel from Baptiste deposit samples. Magnetic separation at bench and pilot scale with different magnetic field strengths is evaluated as a concentration method for awaruite. Mineralogical information is provided to support the results and also to briefly assess the variability of DTR nickel within the deposit. The Baptiste deposit is unique and will benefit from a sound scientific understanding of the process solution as well as other ongoing work. If successful, the outcome will lead to the development of a mine. With greater than 2-billion tonnes of inferred resource, the mine would represent a significant new source of nickel globally. Keywords: Nickel ore processing, magnetic separation , awaruite, magnetite

Jan 1, 2020

By Lene Hansen

Sulphuric acid plants now and then see unexpected increases in SO2 emissions. Our experience is that it is not always easy for the acid plants to pin point the exact reason for the SO2 increase. Sometimes a catalyst bed is sacrificed even though reliable emperature readings and gas analyses could have verified satisfactory activity, hence the leaking heat exchanger is never discovered and after the shutdown the SO2 emissions are still too high. This paper will look into some basic catalyst management tools: Good record keeping is a necessity for collection of representative catalyst samples, reliable operating data is an inevitable starting point for all analysis and trending of operating data is a must for plant optimisation and troubleshooting. In addition these catalyst management tools will give a continuous updated knowledge of the catalyst status in each bed providing the basis for a more effective replacement strategy. The most typical reasons for increasing SO2 emissions will be presented together with easy guidelines for cross-checking of operating data, temperature optimisation and good record keeping.

Jan 1, 2009

By A. H. Swart, M. F. Handley

Unplanned stope panel collapses occur on most near-surface and shallow mines in South Africa. Although these incidents often occur during blasting, they pose a major threat to the safety of underground workers and the economic extraction of orebodies. Most stope panel collapses occur due to excessive panel lengths that are not designed according to a systematic design procedure or methodology. Instead, panel lengths are often dictated by the equipment in use and by previous experience under similar conditions. Hence, a rock engineering design methodology for the design of stable stope panels between pillars is of vital importance for optimum safety and production in shallow mining operations. Using the proposed design methodology described in this paper, rock mechanics practitioners and mine planners should be able to identify and quantify the critical factors influencing the stability of stope panels. The critical factors should then be used as input to the design of stable stope panels that will provide the necessary safe environment for underground personnel working in stopes. The proposed design methodology is an iterative process, which includes aspects such as rock mass characterization, estimation of rock mass properties, identification of potential failure modes, consideration of appropriate stability analyses and other elements of the rock engineering design process. This process continues after implementation. During monitoring, new data should be included in the database and the design process repeated on a regular basis. Design approaches included in the proposed design methodology include empirical methods such as different rock mass classification methods, analytical methods such as elastic and Voussoir beam analyses, kinematic analyses, probabilistic analyses, and numerical analyses. Keywords: stability, stope panels, design methodology, hard rock mines, shallow mining operations

Jan 1, 2004

By J. J. S. de Beer, F. Hunter, A. F. Neethling

SYNOPSIS The paper describes the rib-pillar extraction method now used at Sigma Colliery in the Orange Free State. In this method, access roadways (with a high safety factor) are developed into a block of coal suitable for total extraction; pillars that have a low safety factor are then formed and extracted immediately. The method, together with the current practices of labour management, has resulted in better utilization of the coal resources and capital, increased production and labour productivity, and improved safety.

Jan 1, 1991

The Water Year Office for South Africa has supplied a provisional list of scientific congresses and meetings due to be held during 1970 with "Water" as the main or secondary theme, as follows: February: SARCCUS conference on "Water for Progress," Lourenco Marques. March 16-20: Annual Congress, Institute for Water Pollution Control, Cape Town. May: Possible S.A. Akademie conference on Cooling Tower Experiments, Pretoria. May: Annual Meeting of Association of Municipal Electricity Undertakings, Potchefstroom. May 27-29: Congress on "Water Resources of Natal", Durban. June 29/July 4: Annual Congress, South African Association for the Advancement of Science, Cape Town. July 2: Joint meeting of South African Association for the Advancement of Science and S.A. Akademie, Stellenbosch. July: Winter School, Federation of University Engineering Students. July: Youth Science Week. Foundation for Education, Science and Technology. July 21-24: The South African Tunneling Conference. September: Proposed SARCCUS conference on water in Nature Conservation, Skukuza. November 16-20: International Convention on "Water for the Future", Pretoria.

By J. M. Stewart

Mining fatality rates in many countries have not changed substantially over the past ten years. This demonstrates not only that there is an inherent risk in mining, but also that current approaches to improving safety need to be rethought. An analysis of productivity and fatality data in the United States, United Kingdom, and South 4frican coalmining industries shows that the impact of legislation on safety is overlain by other significant factors. Although improvements in safety and productivity usually occur together, the data warn that safety legislation can sometimes cause a significant reduction in productivity. Based on the data and experience considered, it is concluded that legislation should be aimed at creating a framework within which a positive attitude towards the implementation of more productive and safer mining methods, work practices, and technology can flourish, rather than attempting to enforce excessively prescriptive provisions. This later approach is even more problematic when safety standards and legislation are transferee from well developed to less developed countries. A legislative framework in which the mine manager is required to take al reasonably practicable measures to procure safe working conditions in accordance with mine-specific codes of practice is outlined. Within that framework, the value of adopting widely accepted standards is recognized. A performance-based external audit arrangement is outlined as a basis for ensuring that detailed attention is focused on those areas most needing improvement.

Jan 1, 1995

By R. R. M. Cousens, W. S. Garrett

SYNOPSIS The paper gives a background to the water hazards of the so-called West Wits Line and refers to some geological aspects of the Wonderfontein Valley in which the West Driefontein mine property lies. It describes the precautions taken against flooding during shaft sinking, development and stoping; these include cover hole drilling with cementation, provision for water storage in worked-out areas, installation of water tight bulkhead doors and pumping capacity well in excess of the mine's normal requirements. The plan of campaign adopted after the inrush took place is explained and the reorganization and expansion of pumping arrangements are discussed. When it became clear that the only means of saving the mine was to construct plugs to isolate the inrush while still maintaining all emergency pumping measures, the work was put in hand with the utmost dispatch. In considering the design of the plugs a number of major factors had to be taken into account. The most vital was the need for speed which was complicated by difficulty of access to the plug sites because of the huge volumes of water flowing in the drives. How this and other factors affecting plug design and construction, leakage problems, sequence of operations and final closure of the valves, were overcome is detailed in the paper. INTRODUCTION The inrush of water into the West Driefontein mine, the biggest gold producer in the world, which began on 26th October, 1968 and continued unabated for 23 days before the flood was stemmed, was unprecedented in the history of mining. Also unprecedented were the tremendous efforts and organization which made it possible to bring the situation under control and so save the mine from being lost for a matter of years. BACKGROUND Before going into details of how the situation was brought under control it is appropriate to consider the background to the event. The water problem on the so-called West Wits Line has been recognized for many years. As far back as 1912 the Pullinger Shaft, situated in the centre of what is now the Venterspost mine property, had to be abandoned because there were no means then available of coping with the large quantity of water encountered. To appreciate what vast quantities of water were involved, it helps to refer to some geological aspects of the Wonderfontein valley in which the West Driefontein property lies. The narrow tabular Witwatersrand gold-bearing beds, which dip at about 25 degrees towards the south, are overlain by a surface layer of dolomite which reaches a maximum thickness of some 4,000 ft at West Driefontein. A number of vertical syenitic dykes intersect the valley more or less at right angles to its course (Fig. 1). These dykes are about 150 ft thick on average and are spaced at about eight-mile intervals in the West Driefontein area. They penetrate both the dolomite and the Witwatersrand beds and as they are impervious to water they divide the valley into a series of large underground water compartments.

Jan 5, 1969

By L. G. Snyman

"South Africa is well endowed with a plethora of valuable minerals, as well as being of world renown for its significant ecological and cultural resources. The unfortunate reality is that these two important attributes often come into collision when developmental decisions are made. Robust environmental planning tools are required to guide such development in areas of heightened sensitivity. Environmental management frameworks are one of the tools that can attempt to achieve the desired developmental and ecological balance by utilizing early identification and mapping of sensitive ecosystems and resources to assist in pre-empting potential future land use conflicts. This paper unpacks the characteristics of environmental management frameworks and further investigates their potential, as well as its current design and implementation challenges. The findings show that environmental management frameworks have the potential to provide meaningful resource information to decision-makers on the opportunities and risks of developments in sensitive areas. They further provide a platform and process through which local stakeholders can voice their opinions and collectively drive the developmental priorities of the identified area.IntroductionAt the core of a harmonious and prosperous society is the balancing of a broad spectrum of needs, rights, and imperatives. As South Africa’s resource and energy needs expand, it becomes increasingly important to safeguard environmental rights and ensure sustainable development through creative measures. The State’s drive for accelerated development to meet the targets in the National Development Plan 2030 is contributing to the growth of invasive developments in previously undeveloped areas. The unfortunate reality is that the heightened tensions between rapid economic growth and environmental sustainability are threatening sensitive areas."

Jan 1, 2017

By P. Kitobo, T. Nduba, D. Mbay, J. B. Vangu, R. Ciband

The flotation plant tailings at Kamoa Copper Mine concentrator were found to contain a high proportion of extremely fine particles. The potential issues with settling these fine solids were resolved by the use of a poly-di-allyl-di-methyl ammonium chloride (DADMAC) coagulant, Flobead DB 45 VHM, in conjunction with a standard anionic polyacrylamide flocculant. This paper outlines some of the issues encountered and how they were resolved at the Kamoa concentrator. The potential to use this process and technology at other sites is also considered

Jan 1, 2023

By R. MacRosty, R. Pula, P. Gebski, W. Braun

"This paper provides a progress update on three tapblock monitoring technologies that Hatch has been developing with our clients for non-ferrous smelting furnaces.The Tapblock Diagnostic System (TDS) is an advanced on-line monitoring system that uses temperature data along with embedded thermal model results to evaluate the condition of a tapblock over its campaign life. Hatch recently installed a second Tapblock Diagnostic System, some details of which are provided in this paper.The Tap-hole Acoustic Monitoring (TAM) system is installed on water-cooled copper tapblocks and uses the noise from the tapping channel to provide a qualitative indication of wear and deterioration of the tapping channel refractory. In addition, TAM can be used to monitor drilling and lancing performance, and potentially could also be used in the future as a guide for automatic drilling and lancing systems (Sadri et al., 2008).The third technology is the use of fibre optic sensors to measure temperature on the hot face and in the tapping channel of a tapblock. Fibre optic technology allows installation of numerous sensors in key locations where they are very sensitive to tapblock condition and also provide more extensive spatial coverage than is possible with traditional instruments. This paper provides an update on our efforts to address issues with premature failure of the sensor cables due to corrosion, and also converting the vast amount of data from the sensor cable into information that can be used by furnace operators."

Jan 1, 2014

By L. M. Falcon

Cassiterite is considered to be the only economically significant tin mineral in the earth's crust, and in its purest form has a tin content of 78,6 per cent. South Africa has limited deposits of the mineral, and by its exploitation contributes about 2 per cent of the world's production. This paper gives a brief history of tin mining in South Africa, which dates back almost 3000 years. Over the intervening years, many tin-mining operations have flourished and as quickly disappeared. At present there are only three tin mines in operation, and a description is given of the methods of mining, concentrating, and smelting that are used. The properties and uses of tin are listed, together with relevant statistics.

Jan 1, 1985

By P. R. Janisch

This paper reviews the sources, production, and technology of gold in South Africa. First of al it details the geographical distribution of gold-bearing materials, together with the mineralogy and distribution of gold within those materials. It goes on to the geological origins, and to the discovery and early exploitation, of the gold deposits. The laws relating to the mining and disposal of the metal are explained, after which an outline is given of gold exploration, processing, and refining. The economics of gold production are discussed briefly, and it is concluded that, although present expertise in the financial and technological aspects of a gold-mining venture have largely reduced the risks involved, one severe risk remains: that the rate of cost inflation will not be matched by the rate of escalation in the gold price.

Jan 1, 1986

By A. A. Snodgaass

This paper reviews lead as a commodity, starting with a brief historical outline and dealing with the various uses of lead in some detail. It then goes on to discuss some statistics in relation to the production and reserves of lead, before sketching its mode of occurence. The topics are approached in regard both to the world and to South Africa, with the emphasis on the later. The mining and concentration of lead at Black Mountain Mine at Aggeneys in the north-western Cape Province are detailed, before a general account is given of the smelting, hydrometalurgical extraction, and refining of lead, together with the processes used in these activities. The paper concludes with a discussion of safety and health in regard to lead and a brief look at the commodity's future.

Jan 1, 1986

By P. W. Ocerbeek

The occurrence, properties, and uses of andalusite, and its advantages over other refractory minerals and materials, are discussed. Ore reserves are given for the five producing areas, and statistics on production, export sales, and prices are included to illustrate the growth of the industry since the early 1960s. The mining and beneficiation procedures are described, with special reference to new techniques in concentration and magnetic separation. As fines dumps represent a considerable source of andalusite, possible methods of recovery are discussed. . The outlook for the future appears favourable, and possible competition from other sources and substitute refractory minerals are mentioned. It is concluded that the industry is in a sound position to maintain South Africa's status as the world's foremost producer and supplier of andalusite.

Jan 1, 1989